Power consumption is a major concern in the design of modern display devices. In particular, modern displays operate by continuously displaying new images, even when the image is a still image that does not change with time. Thus, one conventional method of reducing display power consumption involves employing a frame buffer memory which stores the successive images that have been displayed. For a still image, succeeding image frames are the same as those previously displayed. Thus, the display fetches and displays the stored image instead of processing and displaying new images from the video signal. This allows components such as the system and panel interfaces to be powered down, thus saving power.
However, this method of conserving display power is not without its drawbacks. As one example, this method is performed on a frame-by-frame basis. Thus, if even one line changes from one frame to the next, no power is saved. Also, this method cannot be implemented with some applications, for example those that do not employ a frame buffer or that do not have system and panel interfaces to be powered down. Finally, the required frame buffers can be quite large and thus occupy an excessive area of the display's chip, or may have to be implemented off-chip.
Continuing efforts thus exist to reduce display power consumption in other ways.